Separatable laminated containers, which are also called delamination containers, are used as containers containing cosmetics such as face lotion, shampoo, rinse, liquid soap, beverages, food seasonings, or the like (refer to, for example, Patent Literature 1).
Such a delamination container includes a tubular mouth. The delamination container also has a double structure including the outer layer body and the inner layer body laminated on the inner side of the outer layer body in a manner such that the inner layer body is separatable from the outer layer body. When the outer layer body is squeezed (compressed), a content liquid contained in the inner layer body is dispensed to the outside through the mouth. Once the squeezing of the outer layer body is released, ambient air is introduced between the outer layer body and the inner layer body through the ambient air introduction hole provided in the outer layer body, and the outer layer body is restored to its original shape while the volume of the inner layer body remains reduced. Thus, the delamination container may dispense the content liquid without replacing the content liquid with ambient air. Accordingly, contact between the content liquid remaining in the container and air is limited, and this prevents deterioration and change in quality of the content liquid.
Such a delamination container may be obtained by subjecting a preform (as a container material) to biaxially stretch blow-molding. The preform has been formed in a bottomed tubular shape including the outer layer and the inner layer by, for example, injection molding, direct blow (extrusion blow) molding, or extrusion molding.
A production process of the delamination container generally includes the initial separation processing of separating the inner layer body from the outer layer body in advance. The initial separation processing of the inner layer body is performed after blow-molding of the preform into the delamination container in which pressurized air is supplied into the preform. The initial separation processing is achieved by generating negative pressure inside the inner layer body by sucking out air inside the delamination container. After the initial separation processing, air is blown into the delamination container again to return the inner layer body to the state where it is laminated on the outer layer body. Subsequently, the container is filled with the content liquid. This ensures that the inner layer body may be separated from the outer layer body when the content liquid is dispensed.